The present invention is directed toward an active RF circuit. More particularly, the present invention is directed to increasing the frequency range for maximum linear performance that an active RF circuit can achieve.
Integrated circuits (ICs) are typically assembled in small blocks of semiconducting material known as dies. ICs are produced in large batches on a single wafer, which is cut into many pieces, each of which is a copy of the IC. Each of these pieces is called a die.
Due to cost and size constraints, it is generally desirable to pack as large a number of electronic devices and circuits onto a die as possible, while keeping the size of the die as small as possible. In radio frequency (RF) applications for low frequency operation large valued inductors and capacitors are often needed. While an RF circuit can easily be broad banded by utilizing resistive chokes, the voltage drop across the resistors, caused by the bias current in the IC, reduces the amount of voltage swing, and hence the linear performance, that the RF circuit can produce. Inductive chokes are useful for large signal devices, but inductors have limited frequency coverage ranges and take up precious die area that could be used for building additional circuits, so they are often positioned off-die. The path length between the on-die and off-die components, however, increases the parasitic reactance in the circuit.